1. Field of the Invention
The present invention relates to a device, having a three-dimensional visual sensor mounted to a robot, for three-dimensional measurement of an object, which device is utilized for an application performing a three-dimensional measurement of a workpiece for instance for workpiece ejection, workpiece machining, etc.
2. Description of Related Art
In a three-dimensional measurement of an object such as a workpiece using a three-dimensional visual sensor mounted to a robot, a sensor coordinate system must be coupled in advance with a robot coordinate system. An exemplified method therefor is disclosed in JP 10-63317A relating to a “method for coupling coordinate systems in a robot and visual sensor system.”
In practice, however, an accurate coupling is generally quite difficult to achieve due to various reasons, so that an inevitable coupling error may be caused. Due this coupling error, a measurement error may be caused in a measurement performed while changing the position/orientation of robot, which error is unnegligible depending on application.
Aside from the aforementioned cause, due to the presence of backlash in the robot, a robot motion can cause a minute positional variation depending on the directions (motor rotational directions) in which articulated axes of the robot are operated. In some applications, a measurement error produced by such minute variation in robot position cannot be negligible.